Edible oil, especially the so-called healthy edible oil such as fish oil and soybean oil, contains abundant monounsaturated fatty acids and/or polyunsaturated fatty acids. Studies have shown that unsaturated fatty acids, e.g., omega-3 polyunsaturated fatty acids, have the effect of lowering blood cholesterol levels and reducing the risks of cardiovascular diseases. Yet, due to the presence of double bonds in these unsaturated fatty acids, they are very vulnerable to lipid oxidation, which severely affects quality and shelf life of those oil rich in unsaturated fatty acids.
Antioxidants can be used to prevent excessive lipid oxidation. However, butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), two commonly used antioxidants in lipids, are implicated in a possible role of promoting tumor growth. Vitamin E, another well-known antioxidant, has been shown to be ineffective at least in reducing peroxide values in fish oil. While natural antioxidants, e.g., epigallocatechin gallate (EGCG) from tea and camosic acid from rosemary, bring a reliable safety profile and other desirable health benefits such as anti-cancer effects, they are traditionally deemed unsuitable for use in oil due to their high hydrophilicity.
Clearly, there is a demand for healthy edible oil that can maintain quality over a long shelf life. A need thus exists to find a suitable antioxidant and develop an effective and economical method to improve or preserve oxidative stability of edible oil.